Photoresist monomers, polymers thereof and photoresist compositions containing the same

ABSTRACT

Photoresist monomers of following Formula 1, photoresist polymers thereof, and photoresist compositions containing the same. The photoresist polymer includes a repeating unit comprising the photoresist monomer of Formula 1 as a comonomer and the photoresist composition containing the same have excellent etching resistance, heat resistance and adhesiveness to a wafer, and is developable in aqueous tetramethylammonium hydroxide (TMAH) solution. In addition, the photoresist composition has low light absorbance at 157 nm wavelength, and thus is suitable for a photolithography process using ultraviolet light sources such as VUV (157 nm) in fabricating a minute circuit for a high integration semiconductor device.

BACKGROUND

[0001] 1. Technical Field

[0002] Novel photoresist monomers, polymers thereof and photoresistcompositions containing the same are disclosed. In particular,photoresist monomers are disclosed which are suitable for aphotolithography process using DUV (deep ultraviolet) light sources,particularly VUV (vacuum ultraviolet: 157 nm) in fabricating a minutecircuit for a high integration semiconductor device, photoresistpolymers thereof and photoresist compositions containing the same, andpreparation processes are also disclosed.

[0003] 2. Description of the Related Art

[0004] In general, a useful photoresist for ArF and VUV has a variety ofdesired characteristics, such as low light absorbance at the wavelengthof 193 nm and 157 nm, excellent etching resistance, and excellentadhesiveness to a wafer. In addition, a photoresist should be easilydevelopable in a commercially readily available developing solution,such as 2.38 wt % and 2.6 wt % aqueous tetramethylammonium hydroxide(TMAH) solution.

[0005] Recently, much research has been conducted on resins having ahigh transparency at the wavelength of 248 nm and 193 nm and dry etchingresistance similar to novolac resin. However, most of the photoresistsare not suitable for VUV due to their poor transmittance at 157 nmwavelength.

[0006] Research on polyethylene or polyacrylate containing fluorine hasalso been conducted. Unfortunately, most photoresists containingfluorine with a polyethylene, polystyrene or polyacrylate polymerbackbone have weak etching resistance, low solubility in an aqueous TMAHsolution and poor adhesiveness to the silicon wafer. In addition, thesephotoresists are difficult to mass-produce and are expensive.

[0007] On the other hand, photoresists containing fluorine withalicyclic polymer or maleicanhydride-norbonene polymer backbone havegood adhesiveness to the silicon wafer, low light absorbance at thewavelength of 157 nm and excellent etching resistance compared tophotoresists with polyacrylate backbone.

[0008] Besides the above photoresist containing a photoresist polymer,which is prepared by using butadiene sulfone instead of maleicanhydrideas a comonomer, has a low light absorbance at the wavelength of 157 nmand an excellent etching resistance.

SUMMARY OF THE DISCLOSURE

[0009] Accordingly, novel photoresist monomers, polymers thereof andphotoresist compositions containing the same are disclosed which can beused for a light sources such as ArF (193 nm) and VUV (157 nm).

[0010] Also, a process for forming a photoresist pattern using thephotoresist compositions described above and a semiconductor elementproduced by using the process described above are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a photograph of a photoresist pattern obtained fromExample 6; FIG. 2 is a photograph of a photoresist pattern obtained fromExample 7;

[0012]FIG. 3 is a photograph of a photoresist pattern obtained fromExample 8;

[0013]FIG. 4 is a photograph of a photoresist pattern obtained fromExample 9;

[0014]FIG. 5 is a photograph of a photoresist pattern obtained fromExample 10; and

[0015]FIG. 6 is a VUV spectrum for a photoresist composition obtainedfrom Example 6.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0016] A butadiene sulfone compound represented by following Formula 1used for a photoresist monomer:

[0017] In addition, a photoresist polymer comprises the compound ofFormula 1 as a comonomer. The phororesist polymer comprises a repeatingunit represented by following Formula 2 or Formula 3.

[0018] wherein, R₁ is selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group (—O—), (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group, and —COOR′;

[0019] R₂, R₃, R₅ and R₆ are individually selected from the groupconsisting of H, halogen, (C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogensubstituent(s), (C₁-C₂₀) alkyl containing an ether group, and (C₁-C₂₀)alkyl with halogen substituent(s) and containing an ether group;

[0020] R′, R₄ and R₇ are individually acid labile protecting groups;

[0021] X and Y are individually selected from the group consisting of(C₁-C₁₀) alkylene, O and S;

[0022] n is 0 or 1; and

[0023] the ratio a:b:c falls within the ranges 1-50 mol %: 0-50 mol %:0-80 mol %.

[0024] Preferably, the above repeating unit comprises one or more ofsubstituent(s) which are selected from the group consisting of halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, and (C₁-C20) alkyl with halogensubstituent(s) and containing an ether group. More preferably, theycomprise one or more of substituent(s) which are selected from the groupconsisting of F, (C₁-C₂₀) alkyl, (C₁-C20) perfluoroalkyl, (C₁-C₂₀) alkylcontaining an ether group, (C₁-C₂₀) perfluoroalkyl containing an ethergroup, (C₁-C₂₀) alkyl partially substituted with F, and (C₁-C₂₀) alkylpartially substituted with F and containing an ether group.

[0025] In an embodiment, R₂, R₃, R₅ and R₆ are individually selectedfrom the group consisting of H, F, CH₃ and CF₃.

[0026] And the acid labile protecting group can be any of knownprotective groups which prevent the compound from dissolving in analkaline developing solution. However, under the presence of acid, theacid labile group is substituted with acid, thereby making the compoundsoluble to the alkaline solution.

[0027] Some of conventional acid labile protecting groups are disclosedin U.S. Pat. No. 5,212,043 (May 18, 1993), WO 97/33198 (Sep. 12, 1997),WO 96/37526 (Nov. 28, 1996), EP 0 794 458 (Sep. 10, 1997), EP 0789 278(Aug. 13, 1997), U.S. Pat. No. 6,132,926 (Oct. 17, 2000), U.S. Pat. No.6,143,463 (Nov. 7, 2000), U.S. Pat. No. 6,150,069 (Nov. 21, 2000), U.S.Pat. No. 6,180,316 B1 (Jan. 30, 2001), U.S. Pat. No. 6,225,020 B1 (May1, 2001), U.S. Pat. No. 6,235,448 B1 (May 22, 2001) and U.S. Pat. No.6,235,447 B1 (May 22, 2001). Acid labile protecting groups of thepresent invention are preferably selected from the group consisting of2-methyl 2-adamantyl, hexafluoro isopropyl, 8-ethyl 8-tricyclodecanyl,tert-butyl, tetrahydropyran-2-yl, 2-methyl tetrahydropyran-2-yl,tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl, 1-methoxypropyl,1-methoxy-1-methylethyl, 1-ethoxypropyl, 1-ethoxy-1-methylethyl,1-methoxyethyl, 1-ethoxyethyl, tert-butoxyethyl, 1-isobutoxyethyl and2-acetylmenth-1-yl.

[0028] The above repeating unit of Formula 2 or Formula 3 furthercomprise the following monomer of Formula 4.

[0029] wherein, R₈ is selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, and (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group;

[0030] Z is O or S; and

[0031] m is 0 or 1.

[0032] Some of preferred repeating units of above Formula 2 aredisclosed, but are not limited to, as following Formulas 2a to 2e:

[0033] Some of preferred repeating units of above Formula 3 aredisclosed, but are not limited to, as following Formula 3a:

[0034] The process for preparing of a photoresist polymer comprising therepeating units of Formula 2 or Formula 3 will now be explained in moredetail. Radical polymerizing or anion polymerizing each comonomer canprepare the disclosed repeating unit. For example, the repeating unit ofFormula 2 can be prepared according to the process comprising:

[0035] (a) admixing (i) a monomer of Formula 1, (ii) at least one of themonomer selected from the group consisting of Formula 5 and Formula 6,and optionally (iii) a monomer of Formula 4; and

[0036] (b) adding a radical polymerization initiator into the resultantof step (a) in case of performing radical polymerization; or adding ananion polymerization catalyst into the resultant of step (a) in case ofperforming anion polymerization.

[0037] wherein, R₁ is selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₁₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group, and —COOR′;

[0038] R₂ and R₃ are individually selected from the group consisting ofH, halogen, (C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s),(C₁-C₂₀) alkyl containing an ether group, and (C₁-C₂₀) alkyl withhalogen substituent(s) and containing an ether group;

[0039] R′ and R₄ are individually acid labile protecting groups;

[0040] X and Y are individually selected from the group consisting of(C₁-C₁₀) alkylene, O and S; and

[0041] n is 0 or 1.

[0042] In addition the repeating unit of Formula 3 can be preparedaccording to the process comprising:

[0043] (a) admixing (i) a monomer of Formula 1, (ii) at least one of themonomer selected from the group consisting of Formula 7 and Formula 8,and optionally (iii) a monomer of Formula 4; and

[0044] (b) adding a radical polymerization initiator into the resultantof step (a) in case of performing radical polymerization; or adding ananion polymerization catalyst into the resultant of step (a) in case ofperforming anion polymerization.

[0045] wherein, R₅ and R₆ are individually selected from the groupconsisting of H, halogen, (C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogensubstituent(s), (C₁-C₂₀) alkyl containing an ether group, and (C₁-C₂₀)alkyl with halogen substituent(s) and containing an ether group; and

[0046] R₇ is an acid labile protecting group.

[0047] The repeating unit of Formula 3 can be prepared according to thefollowing process as well as polymerizing each comonomer as describedabove. For example, in case that the repeating unit of Formula 3. onlycomprises monomers of Formula 1, Formula 7 and Formula 8, the processcomprises:

[0048] (a) polymerizing a monomer of Formula 1 and 4-acetoxy styrenederivative by radical polymerization or anion polymerization;

[0049] (b) hydrolyzing the resultant polymer of step (a) to obtain apolymer of 4-hydroxy styrene monomer of the Formula 8; and

[0050] (c) reacting a compound containing acid labile protecting group(R₇) with the resultant of step (b) thereby substituting partialhydrogens of hydroxyl group with acid labile protecting group.

[0051] In the above process, radical polymerization or anionpolymerization are carried out by bulk polymerization or solutionpolymerization.

[0052] In case that it is carried out by solution polymerization, theorganic solvents suitable for polymerization can be cyclohexanone,cyclopentanone, tetrahydrofuran, dimethylformamide, dimethylsulfoxide,dioxane, methylethylketone, benzene, toluene, xylene or mixturesthereof.

[0053] The polymerization initiators can be any conventional one,preferably a radical polymerization initiators such as2,2′-azobisisobutyronitrile (AIBN), benzoyl peroxide, acetyl peroxide,lauryl peroxide, tert-butyl peracetate or di-tert-butyl peroxide.

[0054] And the anion polymerization catalyst can be selected from thegroup consisting of KOH, NaNH₂, alkoxide ion, alkali metal, grignardreagent, and alkyl lithium such as lithium diisopropyl amide or n-BuLi.

[0055] More preferably, after polymerization, the repeating unit issubject to crystallization and/or purification by using diethyl ether,petroleum ether, alkane, alcohol, water or mixtures thereof.

[0056] A photoresist polymer of the present invention comprises theabove repeating unit in the main chain and further comprises othercomonomers or additives as occasion demands.

[0057] In addition, another aspect of the present invention provides aphotoresist composition comprising (i) a photoresist polymer describedabove; (ii) a photoacid generator; and (iii) an organic solvent.

[0058] Any of conventional photoacid generator, which is able togenerate acids when it is exposed to light, can be used. Some ofconventional photoacid generator are disclosed in U.S. Pat. No.5,212,043 (May 18, 1993), WO 97/33198 (Sep. 12, 1997), WO 96/37526 (Nov.28, 1996), EP 0 794 458 (Sep. 10, 1997), EP 0789 278 (Aug. 13, 1997) andU.S. Pat. No. 6,132,926 (Oct. 17, 2000), U.S. Pat. No. 6,143,463 (Nov.7, 2000), U.S. Pat. No. 6,150,069 (Nov. 21, 2000), U.S. Pat. No.6,180,316 B1 (Jan. 30, 2001), U.S. Pat. No. 6,225,020 BI (May 1, 2001),U.S. Pat. No. 6,235,448 B1 (May 22, 2001) and U.S. Pat. No. 6,235,447 B1(May 22, 2001).

[0059] Preferred photoacid generators have relatively low lightabsorbance in the wavelength of 157 nm and 193 nm. More preferredphotoacid generator is phthalimidotrifluoromethane sulfonate,dinitrobenzyltosylate, n-decyl disulfone, naphthylimido trifluoromethanesulfonate or mixtures thereof.

[0060] The photoacid generator can further comprise a compound selectedfrom the group consisting of diphenyl iodide hexafluorophosphate,diphenyl iodide hexafluoroarsenate, diphenyl iodidehexafluoroantimonate, diphenyl p-methoxyphenylsulfonium triflate,diphenyl p-toluenylsulfonium triflate, diphenylp-isobutylphenylsulfonium triflate, diphenyl p-tert-butylphenylsulfoniumtriflate, triphenylsulfonium hexafluoroarsenate, triphenylsulfoniumhexafluoroantimonate, triphenylsulfonium triflate,dibutylnaphthylsulfonium triflate and mixtures thereof.

[0061] Typically, the amount of photoacid generator is from about 0.05to about 10% by weight of the photoresist polymer employed. It has beenfound that when the photoacid generator is used in the amount less thanabout 0.05%, it lowers photosensitivity of the photoresist composition,and when the photoacid generator is used in the amount greater thanabout 10%, it results in a poor pattern formation due to its highabsorption.

[0062] On the other hand, any of conventional organic solvent can beemployed for this invention and some of the conventional one are alsodisclosed in the documents described above. Preferred organic solventsfor photoresist composition is methyl 3-methoxypropionate, ethyl3-ethoxypropionate, propylene glycol methyl ether acetate,cyclohexanone, 2-heptanone, ethyl lactate or mixture thereof.

[0063] The amount of organic solvent can range from about 500 to about2000% by weight of the photoresist polymer to coat the photoresist in awanted thickness. It has been found that when the organic solvent isused in the amount of about 1000 wt %, a thickness of the photoresistwill be about 0.25 μm.

[0064] The present invention also provides a process for forming aphotoresist pattern comprising:

[0065] (a) coating the photoresist composition described above on asubstrate to form a photoresist film;

[0066] (b) exposing the photoresist film to light; and

[0067] (c) developing the exposed photoresist film to obtain aphotoresist pattern.

[0068] The process for forming the photoresist pattern can furtherinclude a soft baking which is preformed before the step (b) and/or apost baking step which is preformed after the step (b). Preferably, thesoft and post baking steps are performed at temperature ranging fromabout 70 to about 200° C.

[0069] Exemplary light sources which are useful for forming thephotoresist pattern include not only VUV but also ArF, KrF, E-beam, EUVor ion beam. Preferably, the irradiation energy in the step (b) is inthe range of between about 1 mJ/cm² and about 100 mJ/cm².

[0070] On the other hand, the step (c) can be performed in alkalinedeveloping solution, which is preferably TMAH aqueous solution with aconcentration ranging from about 0.01 to about 5 wt %.

[0071] In addition, another aspect of the present invention provides asemiconductor device manufactured using the photoresist compositiondescribed above.

[0072] The disclosed polymers and photoresist compositions will now bedescribed in more detail by referring to examples below, which are notintended to be limiting.

[0073] I. Preparation of Photoresist Polymers

EXAMPLE 1 Synthesis of poly(butadiene sulfone/norbonen/2-methyl2-adamantyl trifluoromethyl acrylate)

[0074] To 20 mL of anhydrous tetrahydrofuran was added butadiene sulfone(0.1 mole), norbonene (0.1 mole), 2-methyl 2-adamantyl trifluoromethylacrylate (0.1 mole) and AIBN (0.3 g), and the resulting solution wasreacted at about 65° C. for about 10 hours. Thereafter, a polymer wasprecipitated and filtered in mixture solution of methanol and water,thereby obtaining the entitled polymer of Formula 2a (yield: 67%).

EXAMPLE 2 Synthesis of poly(butadienesulfone/tert-butyl-5-norbonene-2-carboxylate/hexafluoroisopropyltrifluoromethyl acrylate)

[0075] To 25 mL of tetrahydrofuran was added butadiene sulfone (0.1mole), tert-butyl-5-norbonene-2-carboxylate (0.1 mole),hexafluoroisopropyl trifluoromethyl acrylate (0.1 mole) and AIBN (0.5g), and the resulting solution was reacted at about 65° C. for about 10hours. Thereafter, a polymer was precipitated and filtered in mixturesolution of methanol and water, thereby obtaining the entitled polymerof Formula 2b (yield: 56%).

EXAMPLE 3 Synthesis of poly(butadienesulfone/tert-butyl-5-norbonene-2-carboxylate/hexafluoroisopropylmethacrylate)

[0076] To 25 mL of tetrahydrofuran was added butadiene sulfone (0.1mole), tert-butyl-5-norbonene-2-carboxylate (0.1 mole),hexafluoroisopropyl methacrylate (0.1 mole) and AIBN (0.5 g), and theresulting solution was reacted at about 65° C. for about 10 hours.Thereafter, a polymer was precipitated and filtered in mixture solutionof methanol and water, thereby obtaining the entitled polymer of Formula2c (yield: 56%).

EXAMPLE 4 Synthesis of poly(methyl maleimide/butadienesulfone/tert-butyl-5-norbonene-2-carboxylate/hexafluoroisopropylmethacrylate)

[0077] To 25 mL of tetrahydrofuran was added methyl maleimide (50 mL),butadiene sulfone (0.1 mole), tert-butyl-5-norbonene-2-carboxylate (0.1mole), hexafluoroisopropyl methacrylate (0.1 mole) and AIBN (0.5 g), andthe resulting solution was reacted at about 65° C. for about 10 hours.Thereafter, a polymer was precipitated and filtered in mixture solutionof methanol and water, thereby obtaining the entitled polymer of Formula2d (yield: 56%).

EXAMPLE 5 Synthesis of poly(butadiene sulfone/4-ethoxyethoxystyrene/4-hydroxy styene

[0078] (Stage 1) Synthesis of poly(butadiene sulfone/4-acetoxy styrene)

[0079] To 20 mL of anhydrous tetrahydrofuran was added butadiene sulfone(0.1 mole), 4-acetoxy styrene (0.15 mole) and AIBN (0.3 g), and waspassed through nitrogen thereby removing general air. And the resultingsolution was shielded thoroughly and reacted at about 90° C. for about10 hours. Thereafter, a polymer was precipitated and filtered in mixturesolution of methanol and water, thereby obtaining the entitled compound(yield: 56%).

[0080] (Stage 2) Synthesis of poly(butadiene sulfone/4-hydroxy styrene)

[0081] To mixture solution which is 20 mL of methanol and 30 mL of 1Nhydrochloric acid was added poly(butadiene sulfone/4-acetoxy styrene)obtained from Stage 1(0.05 mole). And the resulting solution was reactedat about 50° C. for about 10 hours, thereby obtaining the entitledcompound (yield: 95%).

[0082] (Stage 3) Synthesis of poly(butadiene sulfone/4-ethoxyethoxystyrene/4-hydroxy styrene)

[0083] To 10 mL of tetrahydrofuran was added poly(butadienesulfone/4-hydroxy styrene) obtained from Stage 2(0.04 mole) and sulfuricacid (0.1 mL), and the resulting solution was stirred at roomtemperature for about 10 minutes. And then ethylvinylether was injecteda reactor containing the resulting solution and stirred for about 10hours. Thereafter, a polymer was precipitated and filtered in mixturesolution of methanol and water, thereby obtaining the entitled compoundsubstituted partial hydrogens of hydroxyl group with ethoxyethyl whichis acid labile protecting group (yield: 92%).

[0084] II. Preparation of Photoresist Compositions and Formation ofPatterns

EXAMPLE 6 Preparation of Photoresist Compositions and Formation ofPatterns (1)

[0085] To 100 g of propylene glycol methyl ether acetate (PGMEA) wasadded 10 g of the photoresist polymer obtained from Example 1, 0.06 g ofphthalimidotrifluoromethane sulfonate, and 0.06 g of triphenylsulfoniumtriflate. The polymer was precipitated and filtered in 0.20 μm filter toobtain a photoresist composition.

[0086] The photoresist composition thus prepared was spin-coated onsilicon wafer to form a photoresist film, and soft-baked at about 110°C. for about 90 seconds. After baking, the photoresist was exposed tolight using a ArF laser exposer, and then post-baked at about 110° C.for about 90 seconds. When the post-baking was completed, it wasdeveloped in 2.38 wt % aqueous TMAH solution for about 40 seconds, toobtain 0.12 μm L/S pattern (see FIG. 1).

EXAMPLE 7 Preparation of Photoresist Compositions and Formation ofPatterns (2)

[0087] To 100 g of propylene glycol methyl ether acetate (PGMEA) wasadded 10 g of the photoresist polymer obtained from Example 2, 0.06 g ofphthalimidotrifluoromethane sulfonate, and 0.06 g of triphenylsulfoniumtriflate. The polymer was precipitated and filtered in 0.20 μm filter toobtain a photoresist composition.

[0088] The photoresist composition thus prepared was spin-coated onsilicon wafer to form a photoresist film, and soft-baked at about 110°C. for about 90 seconds. After baking, the photoresist was exposed tolight using a ArF laser exposer, and then post-baked at about 110° C.for about 90 seconds. When the post-baking was completed, it wasdeveloped in 2.38 wt % aqueous TMAH solution for about 40 seconds, toobtain 0.13 μm L/S pattern (see FIG. 2).

EXAMPLE 8 Preparation of Photoresist Compositions and Formation ofPatterns (3)

[0089] To 100 g of propylene glycol methyl ether acetate (PGMEA) wasadded 10 g of the photoresist polymer obtained from Example 3, 0.06 g ofphthalimidotrifluoromethane sulfonate, and 0.06 g of triphenylsulfoniumtriflate. The polymer was precipitated and filtered in 0.20 μm filter toobtain a photoresist composition.

[0090] The photoresist composition thus prepared was spin-coated onsilicon wafer to form a photoresist film, and soft-baked at about 110°C. for about 90 seconds. After baking, the photoresist was exposed tolight using a ArF laser exposer, and then post-baked at about 110° C.for about 90 seconds. When the post-baking was completed, it wasdeveloped in 2.38 wt % aqueous TMAH solution for about 40 seconds, toobtain 0.12 μm L/S pattern (see FIG. 3).

EXAMPLE 9 Preparation of Photoresist Compositions and Formation ofPatterns (4)

[0091] To 100 g of propylene glycol methyl ether acetate (PGMEA) wasadded 10 g of the photoresist polymer obtained from Example 4, 0.06 g ofphthalimidotrifluoromethane sulfonate, and 0.06 g of triphenylsulfoniumtriflate. The polymer was precipitated and filtered in 0.20 μm filter toobtain a photoresist composition.

[0092] The photoresist composition thus prepared was spin-coated onsilicon wafer to form a photoresist film, and soft-baked at about 110°C. for about 90 seconds. After baking, the photoresist was exposed tolight using a ArF laser exposer, and then post-baked at about 110° C.for about 90 seconds. When the post-baking was completed, it wasdeveloped in 2.38 wt % aqueous TMAH solution for about 40 seconds, toobtain 0.13 μm L/S pattern (see FIG. 4).

EXAMPLE 10 Preparation of Photoresist Compositions and Formation ofPatterns (5)

[0093] To 100 g of propylene glycol methyl ether acetate (PGMEA) wasadded 10 g of the photoresist polymer obtained from Example 5, 0.06 g ofphthalimidotrifluoromethane sulfonate, and 0.06 g of triphenylsulfoniumtriflate.

[0094] The polymer was precipitated and filtered in 0.20 μm filter toobtain a photoresist composition.

[0095] The photoresist composition thus prepared was spin-coated onsilicon wafer to form a photoresist film, and soft-baked at about 110°C. for about 90 seconds. After baking, the photoresist was exposed tolight using a ArF laser exposer, and then post-baked at about 110° C.for about 90 seconds. When the post-baking was completed, it wasdeveloped in 2.38 wt % aqueous TMAH solution for about 40 seconds, toobtain 0.13 μm L/S pattern (see FIG. 5).

[0096] Experimental Example—Examination of Absorbance at 157 nm

[0097] Absorbance of photoresist composition obtained from Example 6coated in a thickness of 2500 Å was shown by VUV spectrum of FIG. 6.According to FIG. 6, the absorbance of the photoresist composition ofExample 6 at 157 nm wavelength was 0.25, which was merely a half of theabsorbance of conventional photoresist for KrF or ArF light source at157 nm. Thus, the conventional photoresist composition should be coatedin a thickness of 600˜700 Å or less to satisfy the requisite of lighttransmittance for a lithography process employing 157 nm light source,while the photoresist composition according to the present invention,having high light transmittance for 157 nm light source, can provideefficient pattern even when it coated in a thickness of 1200 Å or more.

[0098] The photoresist composition according to the present inventionensures enhanced etching resistance, as it allows formation ofphotoresist film in a sufficient thickness.

[0099] From Experimental Example, it is noticed that the compositioncomprising the photoresist polymer according to the present inventionhas excellent light transmittance at 157 nm wavelength, so that it canbe usefully employed for a photolithography process using 157 nm lightsource. In addition, from Examples 6 to 10, it is ascertained that thephotoresist composition comprising the photoresist polymer according tothe present invention has effective physical property as a photoresist.

[0100] As discussed earlier, a photoresist pattern having excellentdurability, etching resistance, and developable property can be formedsuccessfully by employing the photoresist composition of this presentinvention. And the photoresist composition of this present invention canbe used in forming a minute pattern below 1G DRAM as well as 4G and 16G.Moreover, the photoresist polymer of this present invention has a lowlight absorbance at the 157 nm wavelength, and thus is suitable for aphotolithography using VUV.

What is claimed is:
 1. A photoresist monomer represented by followingFormula 1:


2. A photoresist polymer comprising the photoresist monomer of claim 1.3. The photoresist polymer according to claim 2, wherein the polymercomprises a repeating unit of Formula 2 or Formula 3:

wherein R₁ is selected from the group consisting of H, halogen, (C₁-C₂₀)alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C20) alkylcontaining an ether group (—O—), (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group, and —COOR′; R₂, R₃, R₅ andR₆ are individually selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, and (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group; R′, R₄ and R₇ areindividually acid labile protecting groups; X and Y are individuallyselected from the group consisting of (C₁-C₁₀) alkylene, O and S; n is 0or 1; and the ratio a: b c falls within the ranges 1-50 mol % 0-50 mol%: 0-80 mol %.
 4. The photoresist polymer according to claim 3, whereinthe repeating unit comprises one or more of substituent(s) which areselected from the group consisting of halogen, (C₁-C₂₀) alkyl, (C₁-C₂₀)alkyl with halogen substituent(s), (C₁-C₂₀) alkyl containing an ethergroup, and (C₁-C₂₀) alkyl with halogen substituent(s) and containing anether group.
 5. The photoresist polymer according to claim 3, whereinthe acid labile protecting group is selected from the group consistingof 2-methyl 2-adamantyl, hexafluoro isopropyl, 8-ethyl8-tricyclodecanyl, tert-butyl, tetrahydropyran-2-yl, 2-methyltetrahydropyran-2-yl, tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl, 1-methoxypropyl, 1-methoxy-1-methylethyl,1-ethoxypropyl, 1-ethoxy-1-methylethyl, 1-methoxyethyl, 1-ethoxyethyl,tert-butoxyethyl, 1-isobutoxyethyl and 2-acetylmenth-1-yl.
 6. Thephotoresist polymer according to claim 3, wherein the repeating unitfurther comprises a monomer of Formula
 4.

wherein, R₈ is selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, and (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group; Z is O or S; and m is 0or
 1. 7. The photoresist polymer according to claim 3 or claim 6,wherein the repeating unit is represented by Formulas 2a to 2d orFormula 3a:


8. A process of preparing of a photoresist polymer comprising: (a)admixing (i) a monomer of Formula 1, (ii) at least one of the monomerselected from the group consisting of Formula 5 and Formula 6, and withor without (iii) a monomer of Formula 4; and (b) adding a radicalpolymerization initiator or an anion polymerization catalyst into theresultant of step (a) to obtain a repeating unit of Formula
 2.

wherein, R₁ is selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group, and —COOR′; R₂, R₃ and R₈are individually selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, and (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group; R′ and R₄ are individuallyacid labile protecting groups; X and Y are individually selected fromthe group consisting of (C₁-C₁₀) alkylene, O and S; Z represents O or S;m and n are individually 0 or 1; and the ratio a:b:c falls within theranges 1-50 mol % : 0-50 mol % : 0-80 mol %.
 9. The process according toclaim 8, wherein the step (b) is carried out in a polymerization solventselected from the group consisting of cyclohexanone, cyclopentanone,tetrahydrofuran, dimethylformamide, dimethylsulfoxide, dioxane,methylethylketone, benzene, toluene, xylene and mixtures thereof. 10.The process according to claim 8, wherein the radical polymerizationinitiator is selected from the group consisting of2,2′-azobisisobutyronitrile (AIBN), benzoylperoxide, acetylperoxide,laurylperoxide, tert-butylperoxide and di-tert-butyl peroxide.
 11. Theprocess according to claim 8, wherein the anion polymerization catalystis selected from the group consisting of KOH, NaNH₂, alkoxide ion,alkali metal, grignard reagent and alkyl lithium.
 12. A process ofpreparing of a photoresist polymer comprising: (a) admixing (i) amonomer of Formula 1, (ii) at least one of the monomer selected from thegroup consisting of Formula 7 and Formula 8, and with or without (iii) amonomer of Formula 4; and (b) adding a radical polymerization initiatoror an anion polymerization catalyst into the resultant of step (a) toobtain a repeating unit of Formula
 3.

wherein, R₁ is selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group, and —COOR′; R₅, R₆ and R₈are individually selected from the group consisting of H, halogen,(C₁-C₂₀) alkyl, (C₁-C₂₀) alkyl with halogen substituent(s), (C₁-C₂₀)alkyl containing an ether group, and (C₁-C₂₀) alkyl with halogensubstituent(s) and containing an ether group; R₇ is an acid labileprotecting group; Z represents O or S; m is 0 or 1; and the ratio a:b:cfalls within the ranges 1-50 mol %: 0-50 mol %: 0-80 mol %.
 13. Theprocess according to claim 12, wherein the step (b) is carried out in apolymerization solvent selected from the group consisting ofcyclohexanone, cyclopentanone, tetrahydrofuran, dimethylformamide,dimethylsulfoxide, dioxane, methylethylketone, benzene, toluene, xyleneand mixtures thereof.
 14. The process according to claim 12, wherein theradical polymerization initiator is selected from the group consistingof 2,2′-azobisisobutyronitrile (AIBN), benzoylperoxide, acetylperoxide,laurylperoxide, tert-butylperoxide and di-tert-butyl peroxide.
 15. Theprocess according to claim 12, wherein the anion polymerization catalystis selected from the group consisting of KOH, NaNH₂, alkoxide ion,alkali metal, grignard reagent and alkyl lithium.
 16. A photoresistcomposition comprising: (i) the photoresist polymer comprising thephotoresist monomer of claim 1; (ii) an organic solvent; and (iii) aphotoacid generator.
 17. The photoresist composition according to claim16, wherein the photoacid generator is selected from the groupconsisting of phthalimidotrifluoromethane sulfonate,dinitrobenzyltosylate, n-decyl disulfone and naphthylimidotrifluoromethane sulfonate.
 18. The photoresist composition according toclaim 17, wherein the photoacid generator further comprises a compoundselected from the group consisting of diphenyl iodidehexafluorophosphate, diphenyl iodide hexafluoroarsenate, diphenyl iodidehexafluoroantimonate, diphenyl p-methoxyphenylsulfonium triflate,diphenyl p-toluenylsulfonium triflate, diphenylp-isobutylphenylsulfonium triflate, diphenyl p-tert-butylphenylsulfoniumtriflate, triphenylsulfonium hexafluororphosphate, triphenylsulfoniumhexafluoroarsenate, triphenylsulfonium hexafluoroantimonate,triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate andmixtures thereof.
 19. The photoresist composition according to claim 16,wherein the photoacid generator is present in an amount ranging fromabout 0.05 to about 10% by weight of the photoresist polymer.
 20. Thephotoresist composition according to claim 16, wherein the organicsolvent is selected from the group consisting of methyl3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycol methylether acetate, cyclohexanone, 2-heptanone, ethyl lactate and mixturesthereof.
 21. The photoresist composition according to claim 16, whereinthe organic solvent is present in an amount ranging from about 500 toabout 2000% by weight of the photoresist polymer.
 22. A process forforming a photoresist pattern, comprising: (a) coating a photoresistcomposition of claim 16 on a substrate to form a photoresist film; (b)exposing the photoresist film to light; and (c) developing the exposedphotoresist film to obtain a photoresist pattern.
 23. The processaccording to claim 22, further comprising a soft baking step before step(b) and/or a post baking step after step (b).
 24. The process accordingto claim 23, wherein the soft and post baking steps are individuallyperformed at the temperature ranging from about 70 to about 200° C. 25.The process according to claim 22, wherein the source of the light isselected from the group consisting of VUV, ArF, KrF, E-beam, EUV and ionbeam.
 26. The process according to claim 22, wherein the irradiationenergy of the step (b) ranges from about 1 mJ/cm² to about 100 mJ/cm².27. The process according to claim 22, wherein the step (c) is performedin alkaline developing solution.
 28. A semiconductor elementmanufactured according to the process of claim 22.